1. Field of the Invention
The present invention relates to a speaker apparatus having a cone-shaped diaphragm.
2. Description of the Related Art
Referring to FIG. 1 of the accompanying drawings, illustrated is a conventional speaker apparatus that includes a cone-shaped diaphragm.
This speaker apparatus includes a back plate 1 that has a pole piece 2 extending from a center portion thereof, and a magnet 3 that is located on an annular support portion of the back plate 1. A top plate 4 is placed on the magnet 3 such that a magnetic gap is created between the top plate 4 and pole piece 2. A bobbin 6 that carries a voice coil 5 is positioned in the magnetic gap. The voice coil bobbin 6 is supported for oscillation by a frame 8 via a damper 7. A center portion of a cone-shaped diaphragm 9 is connected to the voice coil bobbin 6. A conical center cap 10 is provided at a top of the voice coil bobbin 6.
The voice coil 5 vibrates (oscillates) together with the bobbin 6 in response to a sound/voice signal current supplied to the voice coil 5. This in turn vibrates the cone-shaped diaphragm 9 and generates a sound.
The sound/voice signal current flows in the voice coil 5 so that heat is generated in the voice coil 5. The above described speaker apparatus therefore suffers from a deteriorated sound quality, which is caused by the heat generated from the voice coil.
The present invention is developed to solve the above described problems, and intends to cool the voice coil efficiently and insure a good sound quality.
According to one aspect of the present invention, there is provided a speaker apparatus including a cone-shaped diaphragm, a voice coil bobbin connected to the diaphragm and made from a material having good thermal transfer characteristics, slits formed in the bobbin, a magnetic circuit for applying a magnetic field to the voice coil, and a center cap placed on a top of the bobbin and made from a material having good heat transfer characteristics.